#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include "md5.h"

#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21


static unsigned char PADDING[64] = {
  	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

#define FF(a, b, c, d, x, s, ac) { \    
	(a) += F ((b), (c), (d)) + (x) + (UINT64)(ac);\
	(a) = ROTATE_LEFT ((a), (s)); \   
	(a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) { \
  (a) += G ((b), (c), (d)) + (x) + (UINT64)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
 }
#define HH(a, b, c, d, x, s, ac) { \
  (a) += H ((b), (c), (d)) + (x) + (UINT64)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
 }
#define II(a, b, c, d, x, s, ac) { \
  (a) += I ((b), (c), (d)) + (x) + (UINT64)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
 }

void initMD5(MD5_Context * md5_context)
{
 	md5_context->count[0] = md5_context->count[1] = 0;
	md5_context->state[0] = 0x67452301;
  	md5_context->state[1] = 0xefcdab89;
  	md5_context->state[2] = 0x98badcfe;
 	md5_context->state[3] = 0x10325476;
}

static void encode(unsigned char *output, UINT64 *input,unsigned int  len);
static void decode(UINT64 *output, unsigned char *input, unsigned int  len);
static void transformMD5 (UINT64 state[4], unsigned char block[64]);

void updateMD5(MD5_Context * md5_context,unsigned char * input,unsigned int input_len)
{
 	unsigned int i = 0;
	unsigned int index = 0;
	unsigned int part_len = 0;

	index = (unsigned int)((md5_context->count[0] >> 3) & 0x3f);
	if((md5_context->count[0] += ((UINT64)input_len << 3)) < ((UINT64)input_len << 3))
		 md5_context->count[1]++;
 	md5_context->count[1] += ((UINT64)input_len >> 29);
	part_len = 64 - index;
	if(input_len >= part_len)
	{
		memcpy((Pointer)&md5_context->buffer[index],(Pointer)input,part_len);
		transformMD5(md5_context->state,md5_context->buffer);
		for(i = part_len; i + 63 < input_len; i += 64 )
			transformMD5(md5_context->state,md5_context->buffer);
		index = 0;
	}
	else
	{	
		i = 0;
	}
	memcpy((Pointer)&md5_context->buffer[index], (Pointer)&input[i], input_len-i);
}

void finishMD5 (unsigned char digest[16],MD5_Context *md5_context)
{
 	unsigned char bits[8];
 	unsigned int index, padLen;

 	encode(bits, md5_context->count, 8);

 	index = (unsigned int)((md5_context->count[0] >> 3) & 0x3f);

 	padLen = (index < 56) ? (56 - index) : (120 - index);
 	updateMD5(md5_context, PADDING, padLen);
 	updateMD5(md5_context, bits, 8);

 	encode(digest, md5_context->state, 16);

 	memset((Pointer)md5_context, 0, sizeof(*md5_context));
}


static void transformMD5 (UINT64 state[4], unsigned char block[64])
{
 	UINT64 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

 	decode(x, block, 64);

 	/* Round 1 */
 	FF(a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
 	FF(d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
 	FF(c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
 	FF(b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
 	FF(a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
 	FF(d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
 	FF(c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
 	FF(b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
 	FF(a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
 	FF(d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
 	FF(c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
 	FF(b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
 	FF(a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
 	FF(d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
 	FF(c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
 	FF(b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

 	/* Round 2 */ 
 	GG(a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
 	GG(d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
 	GG(c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
 	GG(b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
 	GG(a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
 	GG(d, a, b, c, x[10], S22,  0x2441453); /* 22 */
 	GG(c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
 	GG(b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
 	GG(a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
 	GG(d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
 	GG(c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
 	GG(b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
 	GG(a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
 	GG(d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
 	GG(c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
 	GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

 	/* Round 3 */ 
 	HH(a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
 	HH(d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
 	HH(c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
 	HH(b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
 	HH(a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
 	HH(d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
 	HH(c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
 	HH(b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
 	HH(a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
 	HH(d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
 	HH(c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
 	HH(b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */
 	HH(a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
 	HH(d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
 	HH(c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
 	HH(b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */

 	/* Round 4 */
 	II(a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
 	II(d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
 	II(c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
 	II(b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
 	II(a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
	II(d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
 	II(c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
 	II(b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
 	II(a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
 	II(d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
 	II(c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
 	II(b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
 	II(a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
 	II(d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
 	II(c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
 	II(b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */

 	state[0] += a;
 	state[1] += b;
 	state[2] += c;
 	state[3] += d;

 	/* Zeroize sensitive information. */
 	memset((Pointer)x, 0, sizeof(x));
}

static void encode(unsigned char *output, UINT64 *input,unsigned int  len)
{
 	unsigned int i, j;

 	for(i = 0, j = 0; j < len; i++, j += 4) {
  		output[j] = (unsigned char)(input[i] & 0xff);
  		output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
  		output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
  		output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
	}
}

static void decode(UINT64 *output, unsigned char *input, unsigned int  len)
{
 	unsigned int i, j;

 	for(i = 0, j = 0; j < len; i++, j += 4)
  		output[i] = ((UINT64)input[j]) | (((UINT64)input[j+1]) << 8) |(((UINT64)input[j+2]) << 16) | (((UINT64)input[j+3]) << 24);
}


